This invention relates to borescopes or endoscopes of the type in which an imager is mounted onto an elongated insertion tube for viewing a concealed target. The invention is more particularly concerned with probes of the type in which a flexible bendable distal tip is remotely steered by manipulation of a control mechanism.
Recently, interest has increased in the use of video instruments for surgical applications to permit a surgeon to carry out a procedure with minimal intervention in the patient. An example of one such video instrument is a laparoscope for performing surgery in the abdominal cavity, where the instrument is inserted through a small incision. Other probes are provided for diagnosis of medical conditions in the colon or in the gastro-enteric tract. Small probes can also be used in eye surgery. Further examples are found in industrial probes, i.e., borescopes, for inspection of equipment such as boilers or steam generators, or of jet engine rotors where non-destructive penetration of the equipment is necessary.
A laparoscope generally has a rigid metal insertion tube for insertion into the patient's body cavity. In a video type laparoscope there is a miniature camera contained in the distal tip of the insertion tube, with a small focusing lens system and a small solid state imager.
In many cases it is desirable to manipulate only the distal end of the tube when inserted within a patient.
Articulated flexible steering sections have often been employed with flexible probes, and many of these have been employed as cable driven steering sections. One successful system employs so-called wobble washers, that is, a series of rings which are separated by beads or spaces, and through which steering cables pass. An example of such a wobble-washer steering system is described in U.S. Pat. No. 4,700,693. These can be arranged for two-way steering (left-to-right and right-to-left) or four way steering (up-down and down-up as well). Four steering cables are employed, two for the left and right directions and two for the up and down directions. The cables pass from the articulated steering section proximally through the insertion tube to a control mechanism within a control housing. The cables of each pair are moved reciprocally. However, it is desirable to include a tension absorbing mechanism in the housing to accommodate strain on the cables resulting from steering. This occurs because the cable path lengths do change slightly as the steering section bends.
It is also desired to make control of steering responsive and to reduce the resistance felt by the surgeon or other operator on the control handle. Another problem was to provide one-hand control of both horizontal and vertical steering, without making the control mechanism cumbersome or uncomfortable, but to accomplish this in a sealed manner which would permit disinfection and sterilization of the device.